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found minus eigenvalues of OLP at kloop=13 k1= 0 k Date: 2005/04/17 11:53 Name: s. j. luo   <sjluo@phys.ntu.edu.tw> Hi, When I use openmx2.3 to do calculation. I find an information "found minus eigenvalues of OLP at kloop=13 k1= 0 k2= 0 k3= 0 and found minus eigenvalues of OLP kloop=13"in the file "*.std". What is it's meaning? and what should i do in the situation? Thanks in advance! sj luo

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Re: found minus eigenvalues of OLP at kloop=13 k1= 0 k ( No.1 ) Date: 2005/04/19 23:17 Name: T.Ozaki Hi, The minus eigenvalue means that the basis set you specified is overcomplete for your system. Since the localized atomic basis set used in OpenMX is not a complete basis set, one may meet such a situation in some case. Especially, this appears when a highly DENSE structure such as FCC and HCP is calculated using MANY basis functions with a LONGER cutoff radius. Once, the basis set becomes overcomplete in a bulk system, then the calculation is invalid because of the division by near zero. In another thread "Num. of grids overlapping with atom * = 0", you have shown your input file. In this file, you seem to use quite longer cutoff radii for H, C, and N, O elements. Maybe, the longer tail of basis functions is the reason why you find the minus eigenvalue of overlap matrix. It would be better to use a basis set with a shorter cutoff for your system. Regards, T.Ozaki

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